Restaurants and other facilities where substantial cooking is done generate substantial amounts of cooking vapors and air containing volatilized or vaporized grease, and removal and disposal of this grease has been and continues to be a problem in the restaurant industry. Such restaurants and the like require kitchen exhaust systems for removing heat, cooking vapors, and the like. There have been numerous proposals to remove grease from the exhaust air both inside and outside the restaurant buildings, but complete removal within the building is virtually impossible. Therefore, some grease vapors pass out of the building through the exhaust system, which typically is in the form of an exhaust fan or fans mounted on the roof of the building and connected with an exhaust duct or ducts passing through the roof. Substantial amounts of condensed or precipitated grease collect about the fan structure and fan housing, from where it flows or drips downwardly onto the roof. However, the corrosive action of cooking grease is such that many roofing materials deteriorate quickly when saturated with grease. Additionally, accumulations of fats and greases pose potential fire hazards on the roof, and also are unsightly and smelly. However, there are many instances where this condensed or precipitated grease is permitted simply to flow or drip onto the roof surface, despite the adverse consequences. It is known to arrange sand boxes or the like beneath the exhaust fan housing on a restaurant roof, but this requires frequent and troublesome maintenance. Other forms of grease collectors have been proposed to catch condensed or precipitated grease, some of these involving the addition of water so as to facilitate removal of the grease through a skimming action. This is of questionable effectiveness, and again requires frequent and troublesome maintenance and attention.
Typical earlier proposals of which I am aware include those shown in King U.S. Pat. No. 3,410,195 issued Nov. 12, 1968, Graswich et al. U.S. Pat. No. 3,324,629 issued June 13, 1967, Donnelly U.S. Pat. No. 3,393,497 issued July 23, 1968, and Donnelly U.S. Pat. No. 3,581,467 issued June 1, 1971. The King and Donnelly patents are basically "in house" removal systems involving baffling, water sprays, water and detergent sprays, centrifugal baffles, etc. The Donnelly patents include removal and collection systems both inside the building and outside the building, including water-supplied catch basins on the roof about the exhaust fan structure for collecting grease and retaining it in the basins through a skimmer arrangement. Despite the numerous proposals for solutions, I am personally aware that there are numerous installations where condensed or precipitated grease simply flows or drips from the exhaust fan and housing onto the surrounding roof, with the detrimental effects previously mentioned.